Trying to push to existing array in callback function [duplicate]

I am trying to push into an existing array inside a callback function. It seems it is getting pushed inside the callback but the array variable is not being updated after completion. Does this have to do with async/await?

  const writeRequest: WriteRequest[] = [];

  try {
    const responseBody = (await s3Client.send(command)).Body as Readable;
    const stream = responseBody.pipe(stripBomStream());

    Papa.parse(stream, {
      header: true,
      step: (result) => {
        const item = createDynamoBody(result.data);
        writeRequest.push(item);
      },
    });

    console.log('writeRequest: ', writeRequest);

I tried using await and sync on the functions but it seems to not work.